I've had seven (7!) knee surgeries in the last 48 years - my knees are so bad that I can't walk for three or four days at a time - that happens several times a year. My only remaining option is new knees (or resurfacing if that technique improves).

There has almost never been a time when I could not ride and the more I ride, even when walking is difficult, the better my knees feel. Last week I could not bend my left knee enough to walk normally but I raised the seat way up on my mountain bike with road tires, used platform pedals and comfortable shoes, and knocked out 10, 15, and 22 miles in three consecutive days. My knees felt much better after each ride than before.

My left knee is still not working correctly but I did 45 miles (14 mph average) with 2,500 feet of climbing today. My knee felt good riding. Before I started the ride I fiddled with seat height and position to minimize stress on my knees.

Bottom line for me - I'd be a cripple and unable to walk if it weren't for the hundred thousand miles I've ridden in the last 50 years.

Most important considerations:

- fit is critical - seat forward/back and up/down.

- foot rotation (in cleated pedals) is important so you can find the angle that minimizes stress on those poor knees

- fast easy spin is mandatory - I can pound a big gear pretty well but I really feel it in my knees that night.

- I climb in the saddle and REALLY spin - I've always had a triple so I can spin easily - it is not geared real low (34/25 is the lowest gear) but I have lot's of low gears so I'm always turning over at 85+ on climbs

- experiment with your riding position and style - my knees really let me know when I am doing it wrong - they ache all night

Bottom Line - efficient bike riding is great for my totally wrecked knees (not to mention two broken legs and two crushed feet)